A conventional accumulators include a container that seals low pressure refrigerant, a low pressure refrigerant inlet tube that allows the low pressure refrigerant to flow into the container, and a U-shaped tube that allows the low pressure refrigerant in the container to flow out of the container, and the U-shaped tube is covered by an outer tube with a gap between the U-shaped tube and the outer tube. High pressure refrigerant passes through the gap between the U-shaped tube and the outer tube, and the high pressure refrigerant exchanges heat with the low pressure refrigerant in the container and the low pressure refrigerant in the U-shaped tube. This heat exchange allows the low pressure refrigerant in the container and the low pressure refrigerant in the U-shaped tube to be gasified and superheated, and the high pressure refrigerant passing through the gap between the U-shaped tube and the outer tube to be subcooled (for example, see Patent Literature 1).